Electron tube system



July 4, 1933. s Y, WH|TE 1,916,818

ELECTRON TUBE SYSTEM 1 Filed April 18, 1930 swr/VAL INPUT WIT/V555 Patented July 4, 1933 Unirse srArEs PATENT er1-ICE SIDNEY Y. WHITE, OF NEW YORK, N. Y., ASSIGNOR TO EDWARD I-I. LOFTIN, TRUSTEE nnncrnon TUBE SYSTEM Application led April 18,

rIhe present invention relates to improvements in electron tube systems, and more particularly relates to improvements in vthe i structures disclosed and claimed in my copending application Serial Number 381,754

filed July 29, 1929.

An object of my inventiony is the location of a cholre coil, such as the field winding of an electrodynamic speaker, within a direct l@ coupled electron tube system so that the coil reacts with a condenser of the system to form a so-called choke-condenser output system, while the coil or field winding is energized y in such a manner that no additional current L@ drain is imposed upon the source of energy supply, such as the usual rectifier and filter system used in connection with operation from an alternating current source, over that required for the energization of the tubes of the cascaded system.

Other objects of my invention will become apparent as the following description thereof is developed with reference to the accompanying drawingI which diagrammatically illustrates an arrangement of my invention. In the drawing RT designates a rectifier tube energized from a source of alternating` current AC through a power transformer n PT. In shunt to the positive terminal IJ and al the negative or grounded terminal G of the rectifier is connected a filter system comprising a filter choke coil IPC/71, and two filter condensers F01 and F02 connected in the n manner shown.

'3 The positive terminal l? is connected through the choke coil FCI@ to the plate electrodes of tubes VT2 and VTZ, shown connected in parallel, which tubes have their Afilaments energized from a common heating f 4current transformer I-I'I`2. rIhese tubes VTQ and VT2 may be replaced by a single tube having the characteristics of these parallelconnected tubes. The secondary of trans- `former I-IT2 is provided with the usual cen- """'ter-tap potentiometer GT2, which potentiometer is connected through the coil SFC,

shown as the field coil of the well-known electrodynamic speaker, and a. resistance R 50 to the negative terminal G of the rectifier. The cathode of tube Vrll, shown as the 1930. Serial No. 445,285.

conventional screen-grid type, is connected to the terminal G through a stabilizing reis connected to the point A on the resistance R in the manner shown. The screen-grid of tube VTl is connected to a point B of proper potential on the resistance R. The grid of tube VTl is returned to the point A on the resistance R through a signal input system IS, the difference of potential between the cathode of tube VTl and the point A functioning to stabilize the system in the manner described in detail in my copending application hereinbefore referred to. Between the cathode of tube V'Il and the adjustable point D on the resistance R I have connected a socalled hum-bucking condenser HBC, the function of which is likewise described in detail in my copendmg application hereinbefore referred to.

Between the plate electrodes of tubes VT? and V'I"2 and the filaments thereof I have connected a pair of high resistances R and lt carrying current only of the order of the space current of tube VTP I have directly connected the plate of tube VT1 to the grids of tubes VTZ and VT2, and have connected all these electrodes to the point between the resistances R and R by way of resistance CR.

Between the plates of tubes VT2 and VT2 and the filament potentiometer GT2 thereof I have series connected a signal current condenser C2 and the primary of an output or coupling transformer OT, the secondary of which is connected to the voice or signal current coil VC of the loud speaker LS.

The operation of the system is as follows: The sum of the space current flowing through the tubes VT2 and VTZ energizes the speaker field coil SFC and developes a potential between the terminals GT2 and G. Current flowing through the tube VT1 from the potentiometer R', R produces differences of potential in the resistances CR and SR, the potential developed across the resistance CR determining the proper grid bias for the edY of tubes VTl and VT2 flowing therethrough,

all as more specifically stated in my heretofore mentioned (zo-pending application.

When signal current potentials are impressed through thel input system, there are developed amplified signal current potentials across the resistance CR which cause signal current variations inthe ,spacecurrent flow through the tubes V'I2 and VTg.

Tracing the plate-catliode path of the'tubes VT2 and V'I"2 it is seen that the speaker field coil SFC is in series therein, and'therefore energized by the combined current of these tubes, and, in addition, acts as an effective signal current choke coil forcing the; signal' fluctuations tok flow through` the condenser C.2 and the output transformer OT. I-Ium within thesystem is controlled through the adjustment of the point D along the resistance R.r

While I have described my invention asembodied ina specific aparatus, it is to be understood that this structure is'exemplary only and various modifications thereof may be made Without departing from the spirit of myinvention as defined in the clairnsappen'ded hereto.

Having thus described my invention, what I claim is:

l.` In an electron tubeV system, the `comhina-tion of a source of unidirectional current, an indicator ,having a field coil and an input impedance, an output tube the plate of which is directly connected to the positive terminal of said source, the cathode of said tube being connected to the negative terminal of said source by way of said field coil, anda coupling betweeinthe plate and cathode of said tube including in series a condenser and said input impedance of the indicator, whereby said indicator is energized at leastsubstantially with discharge current` from said output tube. l

2; Ina direct-coupled tube system, the combination of a source of unidirectional current,

an indicator having a field coil and an input impedance, a plurality of tube stages direct-coupled in cascade 'relation including an outputvstage the anode side of which is directly connected to the positive terminal of said source and the cathode side of which is connected te the negative terminal of said-l developing element in series therewith, a

coupling-between the anode and cathode side of said output stage including 1n series a condenser and said input impedance of the.V

indicator, and means including said potential developing means for energizing electrodes of Vsaid tube stages whereby the current drain on said sourceis substantially' confined to the greater one of the currents requiredA for the space discharge of said output stage and for the energization of said field coil. Y

In testimony whereof I afiix my signature.

SIDNEY Y. WHITE. 

